gcc/real.h

   1 /* Definitions of floating-point access for GNU compiler.
   2    Copyright (C) 1989-2014 Free Software Foundation, Inc.
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify it under
   7    the terms of the GNU General Public License as published by the Free
   8    Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14    for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GCC; see the file COPYING3.  If not see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_REAL_H
  21 #define GCC_REAL_H
  22
  23 #include "machmode.h"
  24 #include "signop.h"
  25 #include "wide-int.h"
  26 #include "insn-modes.h"
  27
  28 /* An expanded form of the represented number.  */
  29
  30 /* Enumerate the special cases of numbers that we encounter.  */
  31 enum real_value_class {
  32   rvc_zero,
  33   rvc_normal,
  34   rvc_inf,
  35   rvc_nan
  36 };
  37
  38 #define SIGNIFICAND_BITS        (128 + HOST_BITS_PER_LONG)
  39 #define EXP_BITS                (32 - 6)
  40 #define MAX_EXP                 ((1 << (EXP_BITS - 1)) - 1)
  41 #define SIGSZ                   (SIGNIFICAND_BITS / HOST_BITS_PER_LONG)
  42 #define SIG_MSB                 ((unsigned long)1 << (HOST_BITS_PER_LONG - 1))
  43
  44 struct GTY(()) real_value {
  45   /* Use the same underlying type for all bit-fields, so as to make
  46      sure they're packed together, otherwise REAL_VALUE_TYPE_SIZE will
  47      be miscomputed.  */
  48   unsigned int /* ENUM_BITFIELD (real_value_class) */ cl : 2;
  49   unsigned int decimal : 1;
  50   unsigned int sign : 1;
  51   unsigned int signalling : 1;
  52   unsigned int canonical : 1;
  53   unsigned int uexp : EXP_BITS;
  54   unsigned long sig[SIGSZ];
  55 };
  56
  57 #define REAL_EXP(REAL) \
  58   ((int)((REAL)->uexp ^ (unsigned int)(1 << (EXP_BITS - 1))) \
  59    - (1 << (EXP_BITS - 1)))
  60 #define SET_REAL_EXP(REAL, EXP) \
  61   ((REAL)->uexp = ((unsigned int)(EXP) & (unsigned int)((1 << EXP_BITS) - 1)))
  62
  63 /* Various headers condition prototypes on #ifdef REAL_VALUE_TYPE, so it
  64    needs to be a macro.  We do need to continue to have a structure tag
  65    so that other headers can forward declare it.  */
  66 #define REAL_VALUE_TYPE struct real_value
  67
  68 /* We store a REAL_VALUE_TYPE into an rtx, and we do this by putting it in
  69    consecutive "w" slots.  Moreover, we've got to compute the number of "w"
  70    slots at preprocessor time, which means we can't use sizeof.  Guess.  */
  71
  72 #define REAL_VALUE_TYPE_SIZE (SIGNIFICAND_BITS + 32)
  73 #define REAL_WIDTH \
  74   (REAL_VALUE_TYPE_SIZE/HOST_BITS_PER_WIDE_INT \
  75    + (REAL_VALUE_TYPE_SIZE%HOST_BITS_PER_WIDE_INT ? 1 : 0)) /* round up */
  76
  77 /* Verify the guess.  */
  78 extern char test_real_width
  79   [sizeof (REAL_VALUE_TYPE) <= REAL_WIDTH * sizeof (HOST_WIDE_INT) ? 1 : -1];
  80
  81 /* Calculate the format for CONST_DOUBLE.  We need as many slots as
  82    are necessary to overlay a REAL_VALUE_TYPE on them.  This could be
  83    as many as four (32-bit HOST_WIDE_INT, 128-bit REAL_VALUE_TYPE).
  84
  85    A number of places assume that there are always at least two 'w'
  86    slots in a CONST_DOUBLE, so we provide them even if one would suffice.  */
  87
  88 #if REAL_WIDTH == 1
  89 # define CONST_DOUBLE_FORMAT     "ww"
  90 #else
  91 # if REAL_WIDTH == 2
  92 #  define CONST_DOUBLE_FORMAT    "ww"
  93 # else
  94 #  if REAL_WIDTH == 3
  95 #   define CONST_DOUBLE_FORMAT   "www"
  96 #  else
  97 #   if REAL_WIDTH == 4
  98 #    define CONST_DOUBLE_FORMAT  "wwww"
  99 #   else
 100 #    if REAL_WIDTH == 5
 101 #     define CONST_DOUBLE_FORMAT "wwwww"
 102 #    else
 103 #     if REAL_WIDTH == 6
 104 #      define CONST_DOUBLE_FORMAT "wwwwww"
 105 #     else
 106        #error "REAL_WIDTH > 6 not supported"
 107 #     endif
 108 #    endif
 109 #   endif
 110 #  endif
 111 # endif
 112 #endif
 113
 114
 115 /* Describes the properties of the specific target format in use.  */
 116 struct real_format
 117 {
 118   /* Move to and from the target bytes.  */
 119   void (*encode) (const struct real_format *, long *,
 120                   const REAL_VALUE_TYPE *);
 121   void (*decode) (const struct real_format *, REAL_VALUE_TYPE *,
 122                   const long *);
 123
 124   /* The radix of the exponent and digits of the significand.  */
 125   int b;
 126
 127   /* Size of the significand in digits of radix B.  */
 128   int p;
 129
 130   /* Size of the significant of a NaN, in digits of radix B.  */
 131   int pnan;
 132
 133   /* The minimum negative integer, x, such that b**(x-1) is normalized.  */
 134   int emin;
 135
 136   /* The maximum integer, x, such that b**(x-1) is representable.  */
 137   int emax;
 138
 139   /* The bit position of the sign bit, for determining whether a value
 140      is positive/negative, or -1 for a complex encoding.  */
 141   int signbit_ro;
 142
 143   /* The bit position of the sign bit, for changing the sign of a number,
 144      or -1 for a complex encoding.  */
 145   int signbit_rw;
 146
 147   /* Default rounding mode for operations on this format.  */
 148   bool round_towards_zero;
 149   bool has_sign_dependent_rounding;
 150
 151   /* Properties of the format.  */
 152   bool has_nans;
 153   bool has_inf;
 154   bool has_denorm;
 155   bool has_signed_zero;
 156   bool qnan_msb_set;
 157   bool canonical_nan_lsbs_set;
 158 };
 159
 160
 161 /* The target format used for each floating point mode.
 162    Float modes are followed by decimal float modes, with entries for
 163    float modes indexed by (MODE - first float mode), and entries for
 164    decimal float modes indexed by (MODE - first decimal float mode) +
 165    the number of float modes.  */
 166 extern const struct real_format *
 167   real_format_for_mode[MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1
 168                        + MAX_MODE_DECIMAL_FLOAT - MIN_MODE_DECIMAL_FLOAT + 1];
 169
 170 #define REAL_MODE_FORMAT(MODE)                                          \
 171   (real_format_for_mode[DECIMAL_FLOAT_MODE_P (MODE)                     \
 172                         ? (((MODE) - MIN_MODE_DECIMAL_FLOAT)            \
 173                            + (MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1))     \
 174                         : ((MODE) - MIN_MODE_FLOAT)])
 175
 176 #define FLOAT_MODE_FORMAT(MODE) \
 177   (REAL_MODE_FORMAT (SCALAR_FLOAT_MODE_P (MODE)? (MODE) \
 178                                                : GET_MODE_INNER (MODE)))
 179
 180 /* The following macro determines whether the floating point format is
 181    composite, i.e. may contain non-consecutive mantissa bits, in which
 182    case compile-time FP overflow may not model run-time overflow.  */
 183 #define MODE_COMPOSITE_P(MODE) \
 184   (FLOAT_MODE_P (MODE) \
 185    && FLOAT_MODE_FORMAT (MODE)->pnan < FLOAT_MODE_FORMAT (MODE)->p)
 186
 187 /* Accessor macros for format properties.  */
 188 #define MODE_HAS_NANS(MODE) \
 189   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_nans)
 190 #define MODE_HAS_INFINITIES(MODE) \
 191   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_inf)
 192 #define MODE_HAS_SIGNED_ZEROS(MODE) \
 193   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_signed_zero)
 194 #define MODE_HAS_SIGN_DEPENDENT_ROUNDING(MODE) \
 195   (FLOAT_MODE_P (MODE) \
 196    && FLOAT_MODE_FORMAT (MODE)->has_sign_dependent_rounding)
 197
 198 /* True if the given mode has a NaN representation and the treatment of
 199    NaN operands is important.  Certain optimizations, such as folding
 200    x * 0 into 0, are not correct for NaN operands, and are normally
 201    disabled for modes with NaNs.  The user can ask for them to be
 202    done anyway using the -funsafe-math-optimizations switch.  */
 203 #define HONOR_NANS(MODE) \
 204   (MODE_HAS_NANS (MODE) && !flag_finite_math_only)
 205
 206 /* Like HONOR_NANs, but true if we honor signaling NaNs (or sNaNs).  */
 207 #define HONOR_SNANS(MODE) (flag_signaling_nans && HONOR_NANS (MODE))
 208
 209 /* As for HONOR_NANS, but true if the mode can represent infinity and
 210    the treatment of infinite values is important.  */
 211 #define HONOR_INFINITIES(MODE) \
 212   (MODE_HAS_INFINITIES (MODE) && !flag_finite_math_only)
 213
 214 /* Like HONOR_NANS, but true if the given mode distinguishes between
 215    positive and negative zero, and the sign of zero is important.  */
 216 #define HONOR_SIGNED_ZEROS(MODE) \
 217   (MODE_HAS_SIGNED_ZEROS (MODE) && flag_signed_zeros)
 218
 219 /* Like HONOR_NANS, but true if given mode supports sign-dependent rounding,
 220    and the rounding mode is important.  */
 221 #define HONOR_SIGN_DEPENDENT_ROUNDING(MODE) \
 222   (MODE_HAS_SIGN_DEPENDENT_ROUNDING (MODE) && flag_rounding_math)
 223
 224 /* Declare functions in real.c.  */
 225
 226 /* Binary or unary arithmetic on tree_code.  */
 227 extern bool real_arithmetic (REAL_VALUE_TYPE *, int, const REAL_VALUE_TYPE *,
 228                              const REAL_VALUE_TYPE *);
 229
 230 /* Compare reals by tree_code.  */
 231 extern bool real_compare (int, const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 232
 233 /* Determine whether a floating-point value X is infinite.  */
 234 extern bool real_isinf (const REAL_VALUE_TYPE *);
 235
 236 /* Determine whether a floating-point value X is a NaN.  */
 237 extern bool real_isnan (const REAL_VALUE_TYPE *);
 238
 239 /* Determine whether a floating-point value X is finite.  */
 240 extern bool real_isfinite (const REAL_VALUE_TYPE *);
 241
 242 /* Determine whether a floating-point value X is negative.  */
 243 extern bool real_isneg (const REAL_VALUE_TYPE *);
 244
 245 /* Determine whether a floating-point value X is minus zero.  */
 246 extern bool real_isnegzero (const REAL_VALUE_TYPE *);
 247
 248 /* Compare two floating-point objects for bitwise identity.  */
 249 extern bool real_identical (const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 250
 251 /* Extend or truncate to a new mode.  */
 252 extern void real_convert (REAL_VALUE_TYPE *, enum machine_mode,
 253                           const REAL_VALUE_TYPE *);
 254
 255 /* Return true if truncating to NEW is exact.  */
 256 extern bool exact_real_truncate (enum machine_mode, const REAL_VALUE_TYPE *);
 257
 258 /* Render R as a decimal floating point constant.  */
 259 extern void real_to_decimal (char *, const REAL_VALUE_TYPE *, size_t,
 260                              size_t, int);
 261
 262 /* Render R as a decimal floating point constant, rounded so as to be
 263    parsed back to the same value when interpreted in mode MODE.  */
 264 extern void real_to_decimal_for_mode (char *, const REAL_VALUE_TYPE *, size_t,
 265                                       size_t, int, enum machine_mode);
 266
 267 /* Render R as a hexadecimal floating point constant.  */
 268 extern void real_to_hexadecimal (char *, const REAL_VALUE_TYPE *,
 269                                  size_t, size_t, int);
 270
 271 /* Render R as an integer.  */
 272 extern HOST_WIDE_INT real_to_integer (const REAL_VALUE_TYPE *);
 273
 274 /* Initialize R from a decimal or hexadecimal string.  Return -1 if
 275    the value underflows, +1 if overflows, and 0 otherwise.  */
 276 extern int real_from_string (REAL_VALUE_TYPE *, const char *);
 277 /* Wrapper to allow different internal representation for decimal floats. */
 278 extern void real_from_string3 (REAL_VALUE_TYPE *, const char *, enum machine_mode);
 279
 280 extern long real_to_target_fmt (long *, const REAL_VALUE_TYPE *,
 281                                 const struct real_format *);
 282 extern long real_to_target (long *, const REAL_VALUE_TYPE *, enum machine_mode);
 283
 284 extern void real_from_target_fmt (REAL_VALUE_TYPE *, const long *,
 285                                   const struct real_format *);
 286 extern void real_from_target (REAL_VALUE_TYPE *, const long *,
 287                               enum machine_mode);
 288
 289 extern void real_inf (REAL_VALUE_TYPE *);
 290
 291 extern bool real_nan (REAL_VALUE_TYPE *, const char *, int, enum machine_mode);
 292
 293 extern void real_maxval (REAL_VALUE_TYPE *, int, enum machine_mode);
 294
 295 extern void real_2expN (REAL_VALUE_TYPE *, int, enum machine_mode);
 296
 297 extern unsigned int real_hash (const REAL_VALUE_TYPE *);
 298
 299
 300 /* Target formats defined in real.c.  */
 301 extern const struct real_format ieee_single_format;
 302 extern const struct real_format mips_single_format;
 303 extern const struct real_format motorola_single_format;
 304 extern const struct real_format spu_single_format;
 305 extern const struct real_format ieee_double_format;
 306 extern const struct real_format mips_double_format;
 307 extern const struct real_format motorola_double_format;
 308 extern const struct real_format ieee_extended_motorola_format;
 309 extern const struct real_format ieee_extended_intel_96_format;
 310 extern const struct real_format ieee_extended_intel_96_round_53_format;
 311 extern const struct real_format ieee_extended_intel_128_format;
 312 extern const struct real_format ibm_extended_format;
 313 extern const struct real_format mips_extended_format;
 314 extern const struct real_format ieee_quad_format;
 315 extern const struct real_format mips_quad_format;
 316 extern const struct real_format vax_f_format;
 317 extern const struct real_format vax_d_format;
 318 extern const struct real_format vax_g_format;
 319 extern const struct real_format real_internal_format;
 320 extern const struct real_format decimal_single_format;
 321 extern const struct real_format decimal_double_format;
 322 extern const struct real_format decimal_quad_format;
 323 extern const struct real_format ieee_half_format;
 324 extern const struct real_format arm_half_format;
 325
 326
 327 /* ====================================================================== */
 328 /* Crap.  */
 329
 330 #define REAL_ARITHMETIC(value, code, d1, d2) \
 331   real_arithmetic (&(value), code, &(d1), &(d2))
 332
 333 #define REAL_VALUES_IDENTICAL(x, y)     real_identical (&(x), &(y))
 334 #define REAL_VALUES_EQUAL(x, y)         real_compare (EQ_EXPR, &(x), &(y))
 335 #define REAL_VALUES_LESS(x, y)          real_compare (LT_EXPR, &(x), &(y))
 336
 337 /* Determine whether a floating-point value X is infinite.  */
 338 #define REAL_VALUE_ISINF(x)             real_isinf (&(x))
 339
 340 /* Determine whether a floating-point value X is a NaN.  */
 341 #define REAL_VALUE_ISNAN(x)             real_isnan (&(x))
 342
 343 /* Determine whether a floating-point value X is negative.  */
 344 #define REAL_VALUE_NEGATIVE(x)          real_isneg (&(x))
 345
 346 /* Determine whether a floating-point value X is minus zero.  */
 347 #define REAL_VALUE_MINUS_ZERO(x)        real_isnegzero (&(x))
 348
 349 /* IN is a REAL_VALUE_TYPE.  OUT is an array of longs.  */
 350 #define REAL_VALUE_TO_TARGET_LONG_DOUBLE(IN, OUT)                       \
 351   real_to_target (OUT, &(IN),                                           \
 352                   mode_for_size (LONG_DOUBLE_TYPE_SIZE, MODE_FLOAT, 0))
 353
 354 #define REAL_VALUE_TO_TARGET_DOUBLE(IN, OUT) \
 355   real_to_target (OUT, &(IN), mode_for_size (64, MODE_FLOAT, 0))
 356
 357 /* IN is a REAL_VALUE_TYPE.  OUT is a long.  */
 358 #define REAL_VALUE_TO_TARGET_SINGLE(IN, OUT) \
 359   ((OUT) = real_to_target (NULL, &(IN), mode_for_size (32, MODE_FLOAT, 0)))
 360
 361 /* Real values to IEEE 754 decimal floats.  */
 362
 363 /* IN is a REAL_VALUE_TYPE.  OUT is an array of longs.  */
 364 #define REAL_VALUE_TO_TARGET_DECIMAL128(IN, OUT) \
 365   real_to_target (OUT, &(IN), mode_for_size (128, MODE_DECIMAL_FLOAT, 0))
 366
 367 #define REAL_VALUE_TO_TARGET_DECIMAL64(IN, OUT) \
 368   real_to_target (OUT, &(IN), mode_for_size (64, MODE_DECIMAL_FLOAT, 0))
 369
 370 /* IN is a REAL_VALUE_TYPE.  OUT is a long.  */
 371 #define REAL_VALUE_TO_TARGET_DECIMAL32(IN, OUT) \
 372   ((OUT) = real_to_target (NULL, &(IN), mode_for_size (32, MODE_DECIMAL_FLOAT, 0)))
 373
 374 extern REAL_VALUE_TYPE real_value_truncate (enum machine_mode,
 375                                             REAL_VALUE_TYPE);
 376
 377 extern REAL_VALUE_TYPE real_value_negate (const REAL_VALUE_TYPE *);
 378 extern REAL_VALUE_TYPE real_value_abs (const REAL_VALUE_TYPE *);
 379
 380 extern int significand_size (enum machine_mode);
 381
 382 extern REAL_VALUE_TYPE real_from_string2 (const char *, enum machine_mode);
 383
 384 #define REAL_VALUE_ATOF(s, m) \
 385   real_from_string2 (s, m)
 386
 387 #define CONST_DOUBLE_ATOF(s, m) \
 388   CONST_DOUBLE_FROM_REAL_VALUE (real_from_string2 (s, m), m)
 389
 390 #define REAL_VALUE_FIX(r) \
 391   real_to_integer (&(r))
 392
 393 /* ??? Not quite right.  */
 394 #define REAL_VALUE_UNSIGNED_FIX(r) \
 395   real_to_integer (&(r))
 396
 397 /* ??? These were added for Paranoia support.  */
 398
 399 /* Return floor log2(R).  */
 400 extern int real_exponent (const REAL_VALUE_TYPE *);
 401
 402 /* R = A * 2**EXP.  */
 403 extern void real_ldexp (REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *, int);
 404
 405 /* **** End of software floating point emulator interface macros **** */
 406 \f
 407 /* Constant real values 0, 1, 2, -1 and 0.5.  */
 408
 409 extern REAL_VALUE_TYPE dconst0;
 410 extern REAL_VALUE_TYPE dconst1;
 411 extern REAL_VALUE_TYPE dconst2;
 412 extern REAL_VALUE_TYPE dconstm1;
 413 extern REAL_VALUE_TYPE dconsthalf;
 414
 415 #define dconst_e()  (*dconst_e_ptr ())
 416 #define dconst_third()  (*dconst_third_ptr ())
 417 #define dconst_sqrt2()  (*dconst_sqrt2_ptr ())
 418
 419 /* Function to return the real value special constant 'e'.  */
 420 extern const REAL_VALUE_TYPE * dconst_e_ptr (void);
 421
 422 /* Returns the special REAL_VALUE_TYPE corresponding to 1/3.  */
 423 extern const REAL_VALUE_TYPE * dconst_third_ptr (void);
 424
 425 /* Returns the special REAL_VALUE_TYPE corresponding to sqrt(2).  */
 426 extern const REAL_VALUE_TYPE * dconst_sqrt2_ptr (void);
 427
 428 /* Function to return a real value (not a tree node)
 429    from a given integer constant.  */
 430 REAL_VALUE_TYPE real_value_from_int_cst (const_tree, const_tree);
 431
 432 /* Given a CONST_DOUBLE in FROM, store into TO the value it represents.  */
 433 #define REAL_VALUE_FROM_CONST_DOUBLE(to, from) \
 434   ((to) = *CONST_DOUBLE_REAL_VALUE (from))
 435
 436 /* Return a CONST_DOUBLE with value R and mode M.  */
 437 #define CONST_DOUBLE_FROM_REAL_VALUE(r, m) \
 438   const_double_from_real_value (r, m)
 439 extern rtx const_double_from_real_value (REAL_VALUE_TYPE, enum machine_mode);
 440
 441 /* Replace R by 1/R in the given machine mode, if the result is exact.  */
 442 extern bool exact_real_inverse (enum machine_mode, REAL_VALUE_TYPE *);
 443
 444 /* Return true if arithmetic on values in IMODE that were promoted
 445    from values in TMODE is equivalent to direct arithmetic on values
 446    in TMODE.  */
 447 bool real_can_shorten_arithmetic (enum machine_mode, enum machine_mode);
 448
 449 /* In tree.c: wrap up a REAL_VALUE_TYPE in a tree node.  */
 450 extern tree build_real (tree, REAL_VALUE_TYPE);
 451
 452 /* Calculate R as X raised to the integer exponent N in mode MODE.  */
 453 extern bool real_powi (REAL_VALUE_TYPE *, enum machine_mode,
 454                        const REAL_VALUE_TYPE *, HOST_WIDE_INT);
 455
 456 /* Standard round to integer value functions.  */
 457 extern void real_trunc (REAL_VALUE_TYPE *, enum machine_mode,
 458                         const REAL_VALUE_TYPE *);
 459 extern void real_floor (REAL_VALUE_TYPE *, enum machine_mode,
 460                         const REAL_VALUE_TYPE *);
 461 extern void real_ceil (REAL_VALUE_TYPE *, enum machine_mode,
 462                        const REAL_VALUE_TYPE *);
 463 extern void real_round (REAL_VALUE_TYPE *, enum machine_mode,
 464                         const REAL_VALUE_TYPE *);
 465
 466 /* Set the sign of R to the sign of X.  */
 467 extern void real_copysign (REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 468
 469 /* Check whether the real constant value given is an integer.  */
 470 extern bool real_isinteger (const REAL_VALUE_TYPE *c, enum machine_mode mode);
 471
 472 /* Write into BUF the maximum representable finite floating-point
 473    number, (1 - b**-p) * b**emax for a given FP format FMT as a hex
 474    float string.  BUF must be large enough to contain the result.  */
 475 extern void get_max_float (const struct real_format *, char *, size_t);
 476
 477 #ifndef GENERATOR_FILE
 478 /* real related routines.  */
 479 extern wide_int real_to_integer (const REAL_VALUE_TYPE *, bool *, int);
 480 extern void real_from_integer (REAL_VALUE_TYPE *, enum machine_mode,
 481                                const wide_int_ref &, signop);
 482 #endif
 483
 484 #endif /* ! GCC_REAL_H */